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Thermal and Photophysical Properties of Highly Quadrupolar Liquid‐Crystalline Derivatives of the [ closo ‐B 12 H 12 ] 2− Anion
Author(s) -
Ali Muhammad O.,
Lasseter John C.,
Żurawiński Remigiusz,
Pietrzak Anna,
Pecyna Jacek,
Wojciechowski Jakub,
Friedli Andrienne C.,
Pociecha Damian,
Kaszyński Piotr
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805392
Subject(s) - hyperpolarizability , ion , chemistry , crystallography , vertex (graph theory) , fluorescence , stereochemistry , molecule , organic chemistry , physics , combinatorics , graph , mathematics , quantum mechanics , polarizability
Two series of 1,12‐bis‐zwitterionic derivatives of the [ closo ‐B 12 H 12 ] 2− anion ( B ), containing either two 4‐alkoxypyridinium groups ( 1B[ n ]‐ p ) or one 4‐alkoxypyridinium and one 4‐pentylthianium groups ( 2B[ n ]‐ p ), were prepared and their structural (XRD, DFT), thermal, and photophysical properties were compared with those of the analogous derivatives of the [ closo ‐B 10 H 10 ] 2− anion ( 1A[ n ]‐ p and 2A[ n ]‐ p ). Some 1,7‐derivatives of B were isolated and investigated. Both series 1[ n ] and 2[ n ] exhibit nematic and crystalline polymorphism; the 12‐vertex derivatives ( B ) have higher transition temperatures than those of the 10‐vertex analogues ( A ). All compounds fluoresce with quantum yields higher for 1B ( Φ F =0.37 for 1B[7]‐ p and Φ F =0.27 for 2B[7]‐ p ) than those for the 10‐vertex analogues ( Φ F =0.04 for 2A[5]‐ p ). DFT calculations demonstrate an order of magnitude lower first hyperpolarizability, β (−ω,ω,0) , for 2B[7]‐ p than that for the 10‐vertex analogue 2A[7]‐ p (1.7×10 −30 vs. 18.9×10 −30 esu at ω =0).